Numerous window shade configurations have been devised or proposed. In designing a window shade, a number of factors are considered. The primary objectives commonly sought in window shade designs include obtaining a desirable degree of privacy while achieving an aesthetically pleasing appearance so as to enhance, and not diminish, the decor of the room with which the window shade i used. It is also important that the window shade or shades be readily operable or manipulatable so that the degree of privacy afforded by the window shade(s) can be varied and, concomitantly, so that the window shade(s) can be selectively adjustable to a number of desirable, different positions.
In one known window shade construction, a pair of window shades are positioned in a window frame in a stacked relationship, i.e., with one window shade being located vertically on top of the other shade. In U.S. Pat. No. 4,733,710 issued Mar. 29, 1988, to Haines and entitled "Vehicular Shade," such a construction is disclosed wherein one of the two vertically stacked shades is made of an opaque material while the other of the two shades is made of a translucent or screen-like material. The user can selectively cover the window with the opaque pleated shade, the translucent pleated shade or a combination of both. For example, if the bottom of the two vertically disposed shades is opaque and lowered first, then the window is covered by the opaque material. Conversely, lowering the translucent pleated shade progressively collapses the opaque shade and at the same time extends coverage of the upper translucent pleated shade over the window. U.S. Pat. No. 4,733,711 issued Mar. 29, 1988, to Schon and entitled "Folding Blind, Composite Folding Blind and Coupling Strip Therefore" also discloses a pair of vertically stacked window shades. In the double stacked embodiment of FIG. 8, each of the two shade constructions includes an intermediate beam, which is movable relative to a fixed beam of the same window shade assembly and is also movable relative to the intermediate beam and the fixed beam of the other window shade assembly. This patent also discloses a window shade construction in FIG. 3, for example, whereby the pleated shades can be selectively moved from one or both of the top and bottom of the fixed beams of the window shade assembly. U.S. Pat. No. 3,465,806 issued Sept. 9, 1969, to Sulkes and entitled "Pleated Blind Assembly" also discloses a similarly movable single pleated shade, as does U.S. Pat. No. 4,202,395 issued May 13, 1980, to Heck et al. and entitled "Adjustable Shade Construction."
In some window shade designs, a more important factor relates to providing a window shade with significantly enhanced insulative properties. U.S. Pat. No. 4,687,039 issued Aug. 18, 1987, to Chumbley and entitled "Insulative Pleated Window Shade" describes a pair of window shades that are disposed in a front-to-back relationship along the depth or thickness of the window frame. Each of the two shades has one vacuum deposited, aluminized reflective layer, which layers face each other. Such layers are important in achieving the desired insulation. Further, the two pleated shades are not independently movable but, rather, move together when the position of the window shade is adjusted relative to the window frame. Another double window shade assembly is disclosed in U.S. Pat. No. 2,350,094 issued May 30, 1944, to Butts et al.; however, this window shade assembly is intended to block the passage of light while, if desired, providing ventilation within the room having the window shade assembly. Specifically, each of the two pleated shades includes alternating perforated and imperforated panels. The perforations permit the passage of air, when the window is open, but not the passage of light. A similar window shade construction is described in U.S. Pat. No. 2,254,820 issued Sept. 2, 1941, to Donner and entitled "Blind." Another double layer pleated shade is described in U.S. Pat. No. 4,625,786 issued Dec. 2, 1986, to Carter et al. and entitled "Insulated Window Shade Assembly." This assembly includes two layers of window shades wherein each layer is moved together. This window shade configuration is also intended to provide improved insulation at the window area. None of the foregoing three shade assemblies permits independent movement of one shade relative to the other.
A different type of double layer curtain or shade is disclosed in U.S. Pat. No. 4,418,739 issued Dec. 6, 1983, to Woolnough et al. and entitled "Insulating Window Covering." This patent discloses a non-pleated shade used with rollers to provide a double layer using a single shade. U.S. Pat. No. 3,789,904 issued Feb. 5, 1974, to Takazawa entitled "Double Curtain Device" and U.S. Pat. No. 4,344,473 issued Aug. 17, 1982, to Shore and entitled "Means for Separating Light Reflective Fabrics" also relate to double layer shades, which are developed using rollers and a single piece of material.
Although a considerable number of different types of window shades have been disclosed including double layered shades, it remains desirable to provide a window shade that incorporates in one unit the desired features of privacy, pleasing appearance and adjustability of light transmission while being easily operated and which avoids unsightly stacking of pleated window shades. In that regard, none of the known prior art discloses the construction and advantages associated with the independently movable, double pleated shades arranged in a front-to-back relationship disclosed herein for achieving the aforesaid features.